You'll need to give us a better description of the bug you're wanting to imitate. I say this because "duns" could refer to blue duns, one of the other variety of "duns", or the adult stage of a mayfly, otherwise known as the "dun" stage.

Let us know what bug you're trying to imitate, and you'll need to know the size as well. "Small" is not sufficient, as a size 14 may look small to some, but as mayflies go, small is more like a size 20.